Catalytic cracking process employing an acid-reacted metakaolin catalyst

ABSTRACT

Acid reacted metakaolin useful for the preparation of catalyst and catalyst support compositions. The compositions may include solid inorganic oxides, such as zeolites, clay and/or inorganic gels. The compositions are spray dried and calcined to obtain highly active, dense, attrition resistant fluid cracking catalysts, or used in the preparation of formed catalyst supports.

This application is a division of US. Ser. No. 171,496, filed Mar. 14,1988, now U.S. Pat. No. 4,843,052, which is a continuation of US. Ser.No. 786,711 filed Oct. 11, 1985 now abandoned, which is a continuationof US. Ser. No. 552,894 filed Nov. 17, 1983 now abandoned, which is aContinuation-in-Part of US. Ser. Nos. 367,648 filed Apr. 12, 1982 and380,715 filed May 21, 1982, both now abandoned.

Hydrocarbon conversion catalysts such as fluid catalytic crackingcatalysts (FCC) are typically manufactured by spray drying aqueousslurries of catalytically active zeolites and matrix forming componentssuch as inorganic oxide gels and/or clays. The resulting catalystscomprise small particles (microspheres) in which the zeolite crystalsare dispersed throughout a matrix of relatively catalytically inactivegel or sol binder and clay.

It has been found that clay, particularly kaolin, due to its reasonableprice and availability, constitutes a particularly suitable FCC catalystcomponent. The prior art describes preparation of clay based hydrocarbonconversion catalysts that have been thermally and/or chemically treatedto obtain the desired characteristics.

U.S. Pat. No. 2,485,626 describes the preparation of clay based crackingcatalyst wherein kaolin clay is heat treated and reacted with acid toremove alumina from the clay structure. The acid reacted clay is washedfree of soluble components, and formed into catalyst particles.

U.S. Pat. No. 3,406,124 describes a method for preparing catalysts whichcontain crystalline aluminosilicate zeolites dispersed in an inorganicoxide matrix. The matrix contains a clay component which is leached withacid to remove a portion of the alumina of the clay structure as solublealuminum salts. The soluble aluminum salts are precipitated as aluminumhydroxide.

While the prior art describes the preparation of hydrocarbon conversioncatalysts which may comprise or contain thermally/chemically treatedclays, such as calcined/acid leached kaolin, the refining industry isconstantly searching for low-cost catalysts which provide an acceptabledegree of activity and selectivity combined with substantial physicalstrength and attrition resistance.

It is therefore an object of the present invention to provide novel acidreacted metakaolin compositions which may be used in the preparation ofimproved catalytic compositions.

It is another object to provide hydrocarbon conversion catalysts whichare hard, dense and relatively inexpensive to manufacture.

It is yet another object to provide highly active, cost effective FCCcatalysts which contain acid reacted metakaolin in combination withinorganic oxide catalyst components such as zeolites, alumina andsilica-alumina that may be used in the catalytic cracking of a widevariety of hydrocarbon feedstocks.

It is still a further object to provide inexpensive clay-based FCCcatalysts which may be blended with more expensive zeolite containingFCC catalyst and used to process feedstocks that are heavilycontaminated with metals, sulfur and/or nitrogen compounds.

These and still further objects of the present invention will becomereadily apparent to one skilled in the art from the following detaileddescription and specific examples.

Broadly, my invention contemplates novel acid reacted metakaolins andimproved catalytic compositions (including catalysts and catalystsupports) which contain or comprise an acid treated metakaolin that isobtained by heating (calcining) kaolin and reacting the resultingmetakaolin with sufficient acid to react with up to about 25 mol percentof the alumina (Al₂ O₃) present in the kaolin.

More specifically, I have found that dense, hard, attrition resistantcatalytic compositions may be prepared from a novel acid treatedmetakaolin which is obtained by heating (calcining) kaolin to atemperature of about 700° to 910° C., and reacting the resultingmetakaolin with sufficient acid to react with less than about 25 molpercent, and preferably from about 5 to 15 percent of the structuralalumina present in the metakaolin. The compositions, which optionallyinclude zeolites, alumina, silica-alumina and/or clay, are formed intoparticles which may be then heat treated (calcined) at a temperature ofabout 300°-800° C. to obtain hard attrition resistant catalysts orcatalyst supports.

The acid reacted metakaolin is particularly characterized by a surfacearea of about 150 to 500 m² /g, a total pore volume of about 0.15 to0.50 cc/g, an average pore diameter of 20 to 40 Å, and at least about 90percent of the surface area in pores below about 50 Å in diameter.

The acid treated metakaolin catalysts described herein havesubstantially higher activity than the acid leached clays described inthe literature. This low cost, high activity acid treated metakaolinprovides a significant portion of the total cracking activity of thecatalyst. Catalysts with substantial matrix cracking activity are highlydesirable for the cracking of high boiling feedstocks, and for theproduction of high octane gasoline.

While the process is particularly useful for the manufacture of FCCcatalysts which may be used to catalytically crack a wide variety ofhydrocarbon feedstocks my invention also contemplates the preparation ofcatalyst supports which are used in the manufacture of hydroprocessingcatalysts such as hydrocracking, hydrodesulfurization andhydrodemetallization catalysts.

The reaction metakaolin is obtained by thermally treating kaolin at atemperature of from about 700° to 910° C., and preferably 800° to 900°C., for a period greater than about one minute, and preferably 15minutes to 8 hours, and more preferably from 2 minutes to 2 hours. Thethermal treatment, or calcination step, which may be conducted in thepresence of air, converts the raw kaolin into a reactive form which ischaracterized as metakaolin.

The reactive metakaolin is then reacted with a monobasic acid, such ashydrochloric or nitric acid or an acid salt solution thereof such asaluminum chloride, aluminum nitrate, zirconyl chloride, etc.

The quantity of acid reacted with the metakaolin is sufficient to reactwith from about 2 to 25 and preferably from 5 to 15 mol percent of thealumina (Al₂ O₃) present in the metakaolin. The reaction in the case ofhydrochloric acid typically proceeds in accordance with the followingoverall reaction wherein metakaolin has the formula 2 SiO₂.Al₂ O₃.

    2 SiO.sub.2.Al.sub.2 O.sub.3 +1 HCl?[2 SiO.sub.2.(Al.sub.2 O.sub.3).sub.0.9 H.sub.0.6 ]+0.2 Al Cl.sub.3 +0.4 HCl

To achieve the desired level of acid treatment, the quantity of acidused is equal to or less than about 1.5 mols of acid per mol of aluminapresent in the clay. I have found that as little as 0.25 mols of acidper mol of alumina is sufficient to provide the desired acid reactedmetakaolin product in less than about 24 hours. The most preferred levelof acid is about 0.50 to 1.0 mol of acid per mol alumina in themetakaolin. The desired quantity of acid is combined with sufficientwater to provide from about 2.0 to 20 parts by weight acid solution perpart by weight metakaolin. The reaction with acid is conducted at atemperature of from about 60° to 100° C. for a period of from about 1 to24 hours. The resulting acid/metakaolin reaction product contains fromabout 5 to 50 percent by weight clay solids admixed with a liquid phasewhich comprises an aqueous solution of a complex acid/aluminum reactionproduct which has a pH from about 2.0 to 4.0. This acidic aluminumreaction product solution together with the acid leached metakaolinsolids comprises the binder or intermediate which is used in thepreparation of the catalysts and catalyst supports contemplated herein.The ratio of the acid leached clay solid to complex acidic aluminumspecies in solution is from about 8/1 to 9.8/1, preferably 9/1 to 9.5/1parts by weight.

To obtain a cracking catalyst which comprises the acid-metakaolinreaction product described above, the acid-metakaolin reaction mixtureis spray dried or otherwise formed into particles of desired shape andsize. It is also contemplated that the acid reacted metakaolin reactionproduct may be reacted with sufficient base to raise the pH of thereaction mixture to a level of about 5.0 to 9.0 in order to precipitatethe soluble aluminum component prior to forming. Furthermore, thealumina components may be auto-precipitated by holding the reactionmixture for a period in excess of about 3 hours at a temperature of 60°to 100° C. using high clay solids levels.

To prepare fluid cracking catalysts (FCC) the acid reacted metakaolin ismixed with water to obtain a spray drier feed slurry which contains fromabout 20 to 60 percent by weight solids. The slurry is then spray driedusing conventional techniques to obtain microspheroidal FCC catalystparticles which are then calcined either prior to or during use at atemperature of from about 300° to 800° C. These calcined particles maythen be ion exchanged and/or washed to remove undesirable soluble salts.The FCC catalysts of the present invention possess a surface area ofabut 200 to 600 m² /g, a density of about 0.50 to 0.80 g/cc, and amicroactivity of about 40 to 80 volume percent conversion after steamingat 1350° F. with 100 percent steam for 8 hours (ASTM method D3907).Furthermore, the catalysts possess a high degree of attrition resistanceas determined by the methods disclosed in U.S. Pat. No. 4,247,420.

The FCC catalysts of this invention are particularly cost effective forthe catalytic cracking of residual hydrocracking feedstocks whichcontain high levels of contaminating metals (Ni & V), sulfur and/ornitrogen. The catalysts may be blended with standard zeolite promotedcracking catalyst of the type described in U.S. Pat. No. 3,867,308 and3,957,689. It is anticipated that physical blends which contain fromabout 20 to 80 weight percent zeolite FCC in admixture with the FCCcatalysts of this invention will be effective for processing residualfeeds that cause rapid deactivation of conventional catalysts by metalscontamination.

In the event the acid treated metakaolin contemplated herein is utilizedto prepare supports, such as used in the preparation of hydroprocessingcatalysts, the acid metakaolin reaction mixture described above is mixedwith minor amounts of water and formed into extrudates, pills orgranules using conventional forming techniques. It is also contemplatedthat the acid reacted metakaolin may be reacted with a base toprecipitated alumina prior to forming the catalyst supports. Theresultant formed particles are then subjected to calcination eitherprior to or during use at a temperature of from about 300° to 800° C. toobtain hard attrition resistant particles. The resulting calcinedparticles may then be combined with catalytically active metals such asselected from group VI and group VIII of the Periodic Table to obtaincatalysts useful for hydrocracking and hydrodesulfurization,demetallization and so forth. In particular, it is anticipated that fromabout 1 to 20 weight percent non-noble metals, such as cobalt,molybdenum, chromium and nickel may be impregnated or placed upon thecatalyst supports contemplated herein using conventional techniques. Inaddition it is contemplated that from about 0.1 to 2 weight percentnoble metals such as platinum, palladium and rhodium may be combinedwith the supports to obtain useful, catalytically active products.

The indicated above, my invention also contemplates improved catalyticcompositions (including catalysts, catalyst supports and inorganicbinders) which contain the novel acid reacted metakaolin as acombination, binder-catalytically active component.

In particular, I have found that dense, hard, attrition resistantcatalytic compositions may be prepared by combining particulate catalystcomponents with the acid reacted metakaolin which serves as both abinder and catalytically active component of the catalyst. Thecompositions are formed into particles which are then preferably heattreated (calcined) at a temperature of about 300°-800° C. to obtain hardattrition resistant catalysts or catalyst supports.

While the process is particularly useful for the manufacture of zeolitecontaining FCC catalysts, my invention also contemplates the preparationof catalyst supports. These catalysts and supports comprise inortanicoxide gels and hydrogels such as clay, alumina, silica, andsilica-alumina dispersed in or combined with a binder which comprisesthe acid treated metakaolin described above.

To obtain cracking catalysts which contain the acid reacted metakaolin,the acid reacted metakaolin reaction mixture is admixed with the desiredquantity of catalytic components and/or gelled with a base and formedinto catalyst particles. The added components typically comprisecrystalline zeolites such as type X, type Y synthetic faujasite),ultrastable type Y zeolite, ZSM zeolite and/or other desired catalystcomponents such as clay, alumina and silica-alumina hydrogels.Subsequent to mixing the acid reacted metakaolin binder slurry with thecatalyst components, the soluble aluminum components of the binder maybe precipitated as alumina by the addition of a base such as ammoniumhydroxide, or sodium hydroxide. It is also contemplated that the acidreacted metakaolin reaction product may be gelled without added catalystingredients. In the alumina precipitating step, sufficient base is addedto raise the pH of the reaction mixture to a level of about 5.0 to 9.0.

Zeolite components may be initially mixed with the acid-metakaolinbinder slurry in the sodium form, or the zeolites may be pre-exchangedwith hydrogen and/or stabilizing ions such as rare earth ions. Typicalexchanged/thermally treated zeolites comprise the calcined rare earthexchanged type X and Y zeolites (CREX and CREY) described in U.S. Re28,629. In addition, the zeolite component may comprise an ultrastabletype zeolite such as described in U.S. Pat. Nos. 3,293,192 and3,449,070. It is also contemplated that other catalytically activezeolites such as ZSM 5, 11 and mordenite may be utilized alone or asblends with the previously mentioned zeolites.

It is generally found that fluid cracking catalysts (FCC) describedherein will comprise from about 5.0 to 20 parts by weight acidmeta-kaolin binder (dry basis) and from about 95 to 80 parts by weightsolid components such as zeolite, alumina and clays, (including the basegelled acid leached metakaolin described herein). In a typical processof the invention the binder is thoroughly admixed with the solidcomponents to obtain a spray drier feed slurry which contains from about20 to 60 percent by weight solids. The slurry is then spray dried usingconventional techniques to obtain microspheroidal FCC catalyst particleswhich are then calcined at a temperature of from about 300° to 800° C.These calcined particles may then be ion exchanged and/or washed toremove undesirable soluble salts. Typically, the spray dried product iscontacted with solutions of ammonium sulfate and/or rare earth chlorideions.

In the event the acid treated metakaolin binders contemplated herein areutilized to prepare supports, such as used in the preparation ofhydroprocessing catalysts, the acid metakaolin reaction mixturedescribed above is gelled and/or admixed with the desired solidcomponents which typically comprise zeolites, clay and inorganic oxidegels such as alumina, silica and silica alumina (including the basegelled acid reacted metakaolin described herein). The mixtures whichcomprise from about 5 to 40 parts acid treated kaolin binder and 95 to60 parts inorganic solids may be optionally reacted with a base toprecipitate alumina. The mixtures are then formed into catalystparticles having the desired shape and size. Typical forming techniquessuch as pilling, extruding and granulating may be utilized. Theresultant formed particles are then subjected to calcination and atemperature of from about 300° to 800° C. to obtain hard attritionresistant particles. The resulting calcined particles may then becombined with catalytically active metals such as selected from group VIand group VIII of the Periodic Table to obtain catalysts useful forhydrocracking and hydrodesulfurization, dematallization and so forth. Inparticular, it is found that from about 1 to 20 weight percent non-noblemetals, such as cobalt, molybdenum, chromium and nickel may beimpregnated or placed upon the catalyst supports contemplated hereinusing conventional techniques. In addition it is found that from about0.1 to 2 weight percent noble metals such as platinum, palladium andrhodium may be combined with the supports to obtain useful,catalytically active products.

Having described the basic aspects of the present invention, thefollowing examples are given to illustrate the specific embodimentsthereof. The catalytic activity, expressed as volume percent conversion,of the cracking catalysts described in the examples was determined usingthe procedure of ASTM-D3907.

EXAMPLE 1

This example describes preparation of an acid reacted metakaolincatalytic cracking catalyst of the present invention. 67.5 ml of 37% HClwas diluted to about 600 ml total volume and 200 g of metakaolin, whichhad been prepared by calcining kaolin about 50 minutes at 850° C. in arotary calciner, was added. The resulting slurry was refluxed for 8hours. The product was filtered, washed free of Cl⁻, dried in a forceddraft oven and ground. This sample had a surface area of 284 m² /g, analumina content of 38.8% and a catalytic microactivity of 40.7 after an8 hour, 732° C., 100% steam deactivation.

EXAMPLE 2

This example uses the same HCl level and concentration as well as thesame metakaolin set forth in Example 1, and demonstrates that a highsurface area catalyst is produced when the acid reaction period isextended to 60 hours. 13.5 ml 37.0% HCl was diluted to 120 ml, 40 g ofthe metakaolin described in Example 1 was added, and the resultingslurry was aged at 107° C. in a sealed teflon bottle for 60 hours. Theslurry was then filtered, washed Cl⁻ free and oven dried at 121° C. Theresulting product had a surface area of 436 m² /g, an alumina content of36.6% and a microactivity of 39.9 after the steam deactivation.

EXAMPLE 3

This example indicates that higher levels of acid than used in Examples1 and 2 also given a high surface area catalyst. 59.0 ml of 37.0% HClwas diluted to 300 ml, and added 100 g of the same metakaolin as inExample 1. The resulting slurry was refluxed about 8 hours, filtered,washed Cl⁻ free and oven dried. This sample had a surface area of 277 m²/g, an alumina content of 43.8% and a catalytic activity of 34.8% afterthe steam deactivation.

EXAMPLE 4

This example and examples 5-7 illustrate that undesirably high levels ofHCl reduce the alumina content of the catalyst product and reduce itsactivity. 202.5 ml 37.0% HCl diluted to 750 ml, and 200 g of the samemetakaolin of Example 1 was added. A part of the resulting slurry wasremoved after one-half hour at reflux, filtered, washed Cl⁻ free andoven dried. This sample had a surface area of 157 m² /g, an aluminacontent of 33.3% and an activity of 10.7 after steam deactivation.

EXAMPLE 5

This sample was prepared by the same procedure as Example 4, except that337.5 ml 37.0% HCl was used. This product had a surface area 337 m² /g,an alumina content of 14.1% and an activity of 7.5% after steamdeactivation.

EXAMPLE 6

This sample was prepared by the same procedure as Example 4, except that337.5 ml 37.0% HCl was used. This product had a surface area of 488 m²/g, an alumina content of 14.1% and an activity of 7.5% after steamdeactivation.

EXAMPLE 7

This sample prepared by the same procedure as Example 4, except that 405ml 37.0% after steam deactivation.

Table I below summarizes the results of Examples 1-7.

                                      TABLE I                                     __________________________________________________________________________    Microactivity of Acid Reacted Metakaolin Cracking Catalyst as                 Function of Acid Level                                                              % Stoichiometric                                                                       Time at Reflux                                                                        Surface Area                                                                         % Al.sub.2 O.sub.3 in                           Example #                                                                           HCl      (hrs.)  (m.sup.2 /g)                                                                         Leached Clay                                                                         Microactivity.sup.2                      __________________________________________________________________________    1     17       8       284    38.8   40.7                                     2     17       60      436    36.6   39.9                                     3     29       8       277    43.8   34.8                                     4     50       1/2     157    33.3   10.7                                     5     67       1/2     232    23.6   13.4                                     6     83       1/2     337    14.1    7.5                                     7     100      1/2     488     6.18   7.0                                     __________________________________________________________________________     .sup.1 ASTMD3907 microactivity test after an 8 hour, 732° C., 100%     steam deactivation (vol. % conversion).                                  

EXAMPLE 8

This example shows that the temperature used in the calcination of theclay to obtain metakaolin affects the rate of surface area formation.100 g of a calcined kaolin prepared by heating kaolin clay for about 50minutes at 732° C. was added to separate solutions of 37.1 ml 37.0% HCldiluted to 330 ml. The resulting mixtures were aged for 16, 44 or 51hours. The results summarized in Table II indicate that while thismetakaolin is slower reacting than the metakaolin (840° C.) used inExamples 1-7, high surface area products are obtained when longacid-reaction times are used.

                  TABLE II                                                        ______________________________________                                        Surface Area of 17% Stoichiometric HCl Reacted                                Metakaolin (50 min. @ 732° C.)                                         Time @ 100° C.                                                                       Surface Area (m.sup.2 /g)                                       ______________________________________                                        16            128                                                             44            296                                                             51            303                                                             ______________________________________                                    

EXAMPLE 9

This example shows the effect of acid solution volume/concentration onsurface area development. Using the metakaolin of Example 1 33.5 mlquantities of 37 percent HCl (representing 17 mol % of the acid requiredto react with the alumina present in the metakaolin) were diluted withwater to obtain solutions which ranged from 125 to 300 ml in volume.Table III sets forth results for 6 samples. Although all products havehigh surface area indicating good catalytic activity, the third orfourth samples appear to be optimum concentration levels.

                                      TABLE III                                   __________________________________________________________________________    Effect of Acid Concentration on Surface Area of Reacted Clay                  Product.sup.1                                                                 Sample No.                                                                          Reaction Slurry (Composition)      Surface Area (m.sup.3 /g)            __________________________________________________________________________    1     33.5 ml 37% HCl diluted to 300 ml + 100 g metakaolin (as per                  Example 1)                         386                                  2     33.5 ml 37% HCl diluted to 250 Ml + 100 g metakaolin (as per                  Example 1)                         319                                  3     33.5 ml 37% HCl diluted to 200 ml + 100 g metakaolin (as per                  Example 1)                         378                                  4     33.5 ml 37% HCl diluted to 175 ml + 100 g metakaolin (as per                  Example 1)                         404                                  5     33.5 ml 37% HCl diluted to 150 ml + 100 g metakaolin (as per                  Example 1)                         315                                  6     33.5 ml 37% HCl diluted to 125 ml + 100 g metakaolin (as per                  Example 1)                         268                                  __________________________________________________________________________     .sup.1 All preparations were at 17% of stoichiometric HCl, with 60 hr. ag     at 100° C. in teflon bottles.                                     

EXAMPLE 10

This example shows that nitric acid can be used in the preparation ofthe products of the present invention. 19.3 ml concentrated HNO₃ wasdiluted to 225 ml, and 75 g metakaolin (calcined 50 minutes at 871° C.)was added. Three samples of the mixture were reacted in separate teflonbottles for 4, 6 and 8 hours at 100° C. The results, set forth in TableIV, show that the high surface area product is formed after about 6hours (Samples 2 and 3).

                  TABLE IV                                                        ______________________________________                                        Dilute NHO.sub.3 Reacting of Metakaolin                                       Sample No.                                                                              Hot Age Time (hrs.)                                                                         Surface Area (m.sup.2 /g)                             ______________________________________                                        1         4             118                                                   2         6             236                                                   3         8             314                                                   ______________________________________                                    

EXAMPLE 11

This example shows that selected calcination conditions reduce thereaction time required to obtain high surface area products. Separatesamples of kaolin were put into a hot furnace at temperatures rangingfrom 650° to 927° C. for one hour. 50 g samples of each of the abovecalcined clays were slurried in 150 ml H₂ O containing 16.9 mlconcentrated HCl. The 50 g samples were divided into 3 separate samplesand reacted in teflon bottles for 4, 8 or 16 hours. The results, givenin Table V, indicate the most effective calcination temperature is 850°to 875° C. Clays calcined at 927° C. exhibited much lower reactivity.

                  TABLE V                                                         ______________________________________                                        Product Surface Area as a Function of Calcination                             Temperature and Reaction Time                                                 Calcination Temp.                                                             (°C.).sup.1                                                                        650    732    788  843  871  899  927                             ______________________________________                                        Reaction Time,                                                                            87     31     28   184  126  148  25                              4 hrs.                                                                        Reaction Time,                                                                            25     18     25   340  338  219  28                              8 hrs.                                                                        Reaction Time,                                                                            24     47     36   296  457  220  36                              16 hrs.                                                                       ______________________________________                                         .sup.1 All kaolin calcined 1 hour at the indicated temperature.          

EXAMPLE 12

This example shows that low acid levels can be used to obtain theproduct of this invention. 225 g of calcined kaolin (calcined eitherone-half hour at 899° C., 1 hour at 871° C. or 1 hour at 843° C.) wasslurried in 675 ml solution containing 19.2 ml concentrated HCl. Theresulting slurries were boiled 16 hours under reflux. Each slurry samplewas filtered, washed to remove CL⁻ and oven dried. The results, given inTable VI, indicate substantial surface area development even at thisrelatively low acid level.

                  TABLE VI                                                        ______________________________________                                        Use of 1/24 Stoichiometric HCl on Various Metakaolins                                         Reaction                                                      Clay Calcination Conditions                                                                   Time (Hrs.)                                                                             Surface Area (m.sup.2 /g)                           ______________________________________                                        1/2 hr. @ 899° C.                                                                       8        206                                                 "               12        287                                                 "               14        300                                                 "               16        338                                                 1 hr. @ 843° C.                                                                         8        198                                                 "               12        231                                                 "               14        251                                                 "               16        251                                                 1 hr. @ 871° C.                                                                         8        196                                                 "               10        252                                                 "               12        270                                                 "               14        278                                                 ______________________________________                                    

EXAMPLE 13

This example shows that a salt which can generate H⁺ via hydrolysis canbe used in place of mineral acids. 75 g portions of metakaolin (calcined1/2 hr. at 900°C.) were added to 900 ml solutions containing varyingamounts of AlCl₃. 6H₂ O. The slurries were refluxed, the pH adjusted to7.0 with 14% NH₄ OH, filtered, washed Cl⁻ free and oven dried. Theresults, given in Table VII, clearly show the development of very highsurface area materials even at low AlCl₃. 6H₂ O levels.

                  TABLE VII                                                       ______________________________________                                        Effect of Level of AlCl.sub.3.6H.sub.2 O on Rate of                           Surface Area Development                                                      g AlCl.sub.3.6H.sub.2 O/75 g                                                              Time                                                              Metakaolin  at Reflux (Hrs.)                                                                            Surface Area (m/g).sup.2                            ______________________________________                                        75.3         51/2         278                                                 37.7        8             333                                                 37.7        16            418                                                 25.1        8             313                                                 25.1        16            390                                                 18.9        8             305                                                 18.9        16            428                                                 12.6        8             256                                                 12.6        16            410                                                 ______________________________________                                    

EXAMPLE 14

This example shows that ammoniation of the acid reacted clay slurry justprior to filtration enhances activity. A reacted clay slurry wasprepared and reacted as in Example 1 except that after reacting theslurry pH was adjusted to 6.0 with 14% NH₄ OH prior to filtration. Thesurface area was 326 m² /g and the activity was 49.2, which issubstantially higher than the 40.7 observed for the product obtained inExample 1.

EXAMPLE 15

This example shows that enhanced activity can be obtained byprecipitating alumina in the presence of acid reacted metakaolin. 5,400ml concentrated HCl was diluted to about 48 l with water and 16,000 gmetakaolin (calcined 1 hour at 732° C.) was added. The resulting mixturewas reacted under reflux for 48 hours, filtered, washed 2 times with 10gallons hot H₂ O. This product had a surface area of 283 m² /g. 50 g(dry basis, 104.2 g as is) of this filter cake was dispersed in 1/2 l H₂O containing 26.3 g AlCl₃. 6H₂ O. The pH adjusted to 6.0 with 14% NH₄ OHto precipitate alumina and the product was filtered, washed 2 times with1/2 l hot H₂ O and dried at 120° C. The alumina treated sample had anactivity of 48.6 versus 36.1 for the untreated sample.

EXAMPLE 16

This example shows the preparation of a gelled acid treated metakaolinof the present invention. 150 g of kaolin clay calcined 1/2 hour at 900°C. was added to 1.0 l of solution containing 50.7 ml of 37% HCl. Halfthe slurry boiled under reflux for 4 hours and the other half was boiledfor about 8 hours. Both samples were briefly cooled, the pH adjusted to6.0 with 14% NH₄ OH to gel the alumina components, the slurry filteredand washed 2 times with 1/2 l hot deionized H₂ O and oven dried. Thesurface areas of the 4 and 8 hour refluxed samples were 295 and 402 m²/g. The catalytic activity of the 4 and 8 hour refluxed samples were46.4 and 50.5 respectively following the procedure of ASTM-D3907.

EXAMPLE 17

This example shows that significant enhancement in activity is observedby addition of boehmite to the gelled acid treated metakaolin of thepresent invention. 200 g kaolin clay calcined 1/2 hour at 900° C. wasadded to 2.0 solution containing 67.9 ml 37% HCl and boiled under refluxfor 24 hours. To four separate cooled samples of the above slurry,varying amounts of boehmite were added the pH was adjusted to 7.0 with14% NH₄ OH, the slurry filtered and the filter cake washed 2 times with1/2 l hot deionized H₂ O. The samples were dried and the crackingcatalytic activity of each sample was determined. The activity data,summarized in Table VIII shows that boehmite addition to the gelled acidtreated metakaolin results in significant activity improvement.

                  TABLE VIII                                                      ______________________________________                                        Effect of Added Boehmite on Gelled Acid                                       Reacted Metakaolin Catalysts                                                  % Added Boehmite                                                                              Vol. % Conversion.sup.1                                       ______________________________________                                        0               50.0 (typical)                                                15.0            59.9                                                          17.5            60.0                                                          20.0            59.0                                                          22.5            59.3                                                          ______________________________________                                         .sup.1 ASTMD3907 Volume % conversion measured at 499° C., 16 WHSV,     3 C/O after an 8 hour, 732° C., 100% steam treatment.             

EXAMPLE 18

Samples of hydrothermally acid treated metakaolin were prepared byadding 25 g kaolin (calcined 1/2 hour at 900° C.) to 125 ml H₂ Ocontaining 8.5 ml 37% HCl and heating for the time/temperature indicatedin Table IX in teflon lined high pressure reactors. The slurries werecooled, diluted with water to make a stirrable slurry, the pH adjustedto 7.0 with 14% NH₄ OH, filtered, washed 2 times with 1/2 l hot H₂ O andoven dried at 120° C. The activity of the hydrothermally acid treatedmetakaolin is significantly increased relative to the 100° C. refluxedsample.

                  TABLE IX                                                        ______________________________________                                        Effect of High Temperature Acid Treatment                                     Reaction Temp.                                                                          Reaction Time                                                                             Surface Area                                                                             Activity.sup.2                               (°C.)                                                                            (Hrs.)      (m.sup.2 /g.sup.1)                                                                       (Vol. % Cov.)                                ______________________________________                                        100 (Typical)                                                                           4-24        400        50 (Typical)                                 140       6           413        57.9                                         140       88          526        59.2                                         165       6           392        58.0                                         ______________________________________                                         .sup.1 Surface area measured after a 1 hour at 593° C. thermal         treatment.                                                                    .sup.2 ASTMD3907 volume % conversion measured after an 8 hour, 732.degree     C., 100% steam treatment.                                                

EXAMPLE 19

A sample of kaolin clay having a particle size less than 2.0 micronswhich possessed the initial chemical composition 51.8 weight percentSiO₂, 42.2 percent Al₂ O₃ was calcined for one half hour at 900° C. A300 g sample of the calcined clay was then added to 3 liters of asolution which contained 102 ml of 37 percent HCl. The resulting slurrywas refluxed at a temperature of 100° C. for 4 hours. The reactionmixture was then combined with 500 g of calcined, rare earth exchangedtype Y zeolite (CREY) which contained 0.79 percent Na₂ O, and 2323 g(dry basis) raw kaolin. The slurry was homogenized and subsequentlyspray dried. The physical properties of the resulting catalyst productare summarized in the Table.

EXAMPLE 20

A 9000 g sample of metakaolin, which was obtained by calcining rawkaolin for one-half hour at 900° C., was admixed with 60 of an acidsolution which contained 3042 ml of 37% HCl. This mixture was thenboiled under reflux for seven and one-half hours. The slurry pH wasadjusted to about 6.0 by the addition of 30 percent ammonium hydroxide.The gelled reaction mixture was then filtered, washed twice with 10 galof hot deionized water, and reslurried in approximately 25 gal of hotdeionized water and recovered by filtration. 450 g D.B. (2074 g as is)of this filter cake was dispersed in a blender along with a slurry whichcomprised 500 g of the CREY described in Example 1 and 2175 g (drybasis), 2529 g as is of raw kaolin, and approximately 8,000 g of water.The mixture was homogenized by recirculation through a centrifugal pumpand subsequently spray dried. The physical properties of the catalystobtained in this example are set forth in the Table.

EXAMPLE 21

A 1400 g sample of the metakaolin described in Example 2 was combinedwith 4.2 l of a solution which contained 472.6 ml of 37% HCl dissolvedin water. This mixture was boiled under reflux for 2 hours. The reactionmixture was then combined in the blender with 559.4 g CREY and 2120 g(dry basis) kaolin. The slurry was then thoroughly mixed and spray driedto obtain microspheroidal particles. The catalyst particles were thencalcined 2 hours at 540° C. This sample had the physical propertiesdescribed in the Table.

EXAMPLE 22

A 6750 g sample of the metakaolin described in Example 2 was added to 80l of the solution which contained 2286 ml of 37% HCl. This mixture wasthen boiled under reflux for 7 hours. 6 l of the resulting slurry wascombined with a 2175 g (dry basis) sample of raw kaolin and 434 g (drybasis) CREY. The slurry was then mixed thoroughly, spray dried andcalcined 2 hours at 540° C. The physical properties of the catalystobtained in this example is summarized in the Table.

EXAMPLE 23

This example shows that a portion of the acid leached clay slurry can beused to bind an ammonium hydroxide gelled acid leached clay of the typedescribed in Example 2. 600 g of kaolin was calcined one-half hour at900° C. was added to 6.0 l solution containing 204 ml 37.0% HCl andboiled under reflux for approximately 4 hours. A blended slurry of 180 gas is CREY (0.79% Na₂ O) and 2,215 g dry basis (10,889 g as is) washedammonium hydroxide gelled acid leached clay obtained by the procedureset forth in Example 2 was added. The slurry was thoroughly mixed andspray dried. The properties of this catalyst sample are set forth in theTable.

EXAMPLE 24

A 5,200 g dry basis sample of the washed ammonium hydroxide gelled acidleached metakaolin of Example 2 was slurried in a total of about 30,000g of water and spray dried. The properties are set forth in the Table.

EXAMPLE 25

450 g of the calcined clay described in Example 1 was added to 4.5 lsolution containing 153.0 ml conc. HCl and boiled 4 hours under reflux.To this slurry 500 g of CREY and 2,529 g (raw) kaolin clay were added,the slurry briefly homogenized and spray dried. This sample, ofcomposition 15 percent acid treated clay, 12.5 percent CREY, 72.5percent kaolin clay, had the properties indicated in the Table.

                  TABLE X                                                         ______________________________________                                                           Attrition Resistance                                               Density    Davison Index/                                             Example #                                                                             *ABD/**CD  Jersey Index.sup.(1)                                                                        Microactivity.sup.(2)                        ______________________________________                                        19      0.72/0.81   4/0.6        --                                           20      0.59/0.81  13/0.3        73.4                                         21      0.68/.83   13/2.0        --                                           22      0.70/0.81  14/2.1        --                                           23      0.65/0.86  12/0.3        58                                           24      0.62/0.71  19/1.6        44.                                          25      0.67/.83   14/2.2        70.0                                         ______________________________________                                         .sup.(1) Attrition Resistance measured after calcination for 2 hours at       1000° F. as determined by the method set forth in U.S. Pat. No.        4,247,420.                                                                    .sup.(2) Microactivity volume % conversion as determined by use of the        test as described by Henderson et al at 900° F., 16 WHSV, 3 c/o        after an 8 hour, 1350° F., 100 steam deactivation.                     *ABD  Apparent Bulk Density (g/cc)                                            **CD  Compacted Density (g/cc)                                           

EXAMPLE 26

9.0 kg (dry basis) of kaolin clay was calcined for 1/2 hour at 900° C.and cooled to room temperature. This was added to 75 l of solutioncontaining 3,056 ml 37% HCl and boiled under reflux for 22 hours. Theslurry was cooled, the pH adjusted to 6.5 with 30% NH₄ OH, filtered,washed 3 times with 15 gallons hot water, redispersed in the minimumabout of water to make a pumpable slurry and spray dried.

Pore size distribution data on this sample (after a 2 hour at 538° C.treatment) are summarized in Table XI and FIG. 1. It is noted that theproduct has greater than 90% of its surface area in less than 50Å pores.

EXAMPLE 27

This example shows the effect of addition of a base to gel the slurry onpore size distribution. 100 g (dry basis) kaolin clay was calcined 1hour at 843° C., cooled, then added with rapid agitation to 300 mlsolution containing 33.8 ml 37% HCl, boiled under reflux for 24 hoursand divided in half. One portion was filtered, washed on the filter onetime with 1/2 l hot deionized water and oven dried. This sample isreferred to as the ungelled partially acid leached metakaolin (PALMK).The second portion was gelled by the addition of 14% NH₄ OH to pH 7.0,filtered, washed one time with 1/2 l hot deionized water and oven driedovernight at 121° C. This sample is referred to as gelled PALMK.

Pore size distribution on the gelled and ungelled PALMK (Table XII) &FIG. 2) indicate both are very small pore materials, with the NH₄ OHgelled material having more smaller than 20 Å and greater than 600 Åpores.

EXAMPLE 28

This example shows that hydrothermal treatment of PALMK results in asignificant loss in surface area and shift to larger average porediameters. 50 g calcined kaolin clay (calcined 1 hour at 843° C.) wasadded with rapid agitation to 150 ml solution containing 16.9 ml 37% HCland boiled 7 hours under reflux, cooled to room temperature, the pHadjusted to 6.0 with 14% NH₄ OH, filtered, washed one time with 250 mlhot deionized water and oven dried at 121° C. overnight.

A comparison of the pore structure after a 1 hour at 538° C. treatmentand after an 8 hours, 732° C., 100% steam treatment is given in TableXIII and FIG. 3. Clearly the hydrothermal treatment significantlyreduced surface area and dramatically increased the average porediameter.

EXAMPLE 29

This example shows the high cracking activity obtained with PALMK, evenwith relatively low levels of zeolite promoter. 150 g (as is) of kaolinclay (calcined 1/2 hour at 900° C.) was slurried in 1.0 l H₂ Ocontaining 50.7 ml 37% HCl and boiled under reflux for 7 hours. Theslurry was then divided into three equal samples, with the first sampleadjusted to pH 7.0 with 14% NH₄ OH, filtered, washed twice with 250 mlhot water and oven dried at 121° C. The second sample was adjusted to pH7.0 with 14% NH₄ OH, a blended slurry of low Na₂ O CREY added (2.36 gSiO₂ /Al₂ O₃ basis, 4.5% by weight in the catalyst), the slurryfiltered, washed twice with 250 ml hot water and oven dried at 121° C.The third sample was gelled with 14% NH₄ OH, a blended slurry of 8.82 glow Na₂ O ultrastable zeolite Y added, filtered, washed twice with 250ml hot water and oven dried at 121° C. After oven drying the sampleswere crushed to less than 425 microns in particle size andhydrothermally deactivated for 8 hours, 732° C., 100 steam beforetesting in the microactivity units.

Results, summarized in Table XIV, indicate PALMK by itself (Sample 1)has a high activity, and even at low levels of zeolite additionapproaches the activity of higher CREY zeolite commercial catalysts.Selectivity for the CREY containing sample (Sample 2) versus thecommercial catalyst indicates the PALMK & CREY gives

(1) Improved liquid yields (Gasoline & Distillate);

(2) Reduced bottoms yield (338° C.+);

(3) Increased LCO yields; and

(4) Similar conversion/coke ratios.

EXAMPLE 30

This example shows that while the gelled PALMK has acceptable physicalproperties, these can be significantly improved by addition of aluminasol. A large batch of PALMK was prepared by addition of 6,750 g of clay(calcined 1/2 hour at 900° C.) to 81 l of solution containing 2,286 ml37% HCl and boiling 71/2 hours under reflux. After cooling, the slurrywas adjusted to pH 7.0 with 30% NH₄ OH, filtered, washed twice with 10gallons hot deionized water, reslurried in the minimum water and spraydried.

A second preparation was made by adding 9 kg kaolin clay (calcined 1/2hour at 900° C.) to 60 l of solution containing 3,042 ml 37% HCl andboiled 7 hours under reflux. The slurry was briefly cooled, adjusted topH 7.0 with 30% NH₄ OH, filtered and washed 3 times with 12 gallons hotdeionized water. 7,500 g dry basis (34,600 g as is) of the above cakewas reslurried in the minimum water, the pH adjusted to 5.0 with 10%HCl, 5,632 Chlorhydrol having the composition of about 23.5 wt. % Al₂O₃, 8.0 wt. % Cl added and the slurry spray dried.

Physical properties on the above materials, summarized in Table V,indicate a significant improvement in ABD and D.I./J.I. by the use ofalumina sol.

EXAMPLE 31

The example shows that the acid leached clay slurry can be used as aco-binder to improve attrition resistance. The catalyst without PALMKslurry was prepared by addition of a blended slurry of 375 g SiO₂ /Al₂O₃ basis CREY to 1,277 g Chlorhydrol, then adding 2,703 g as is kaolinclay, mixing well and spray drying. The sample with PALMK was preparedby adding 450 g clay (calcined 1/2 hour at 900° C.) to 3.5 l solutioncontaining 153 ml 37% HCl and boiling for 4 hours, to this was added theCREY slurry and Chlorhydrol and 2,180 g as is kaolin clay. Physicalproperties (Table XVI) show the sample containing the acid leached clayco-binder to have significantly reduced D.I./J.I. compared to thecatalyst prepared without PALMK binder.

EXAMPLE 32

This example shows that addition of PALMK produces catalysts allowingreduced usage of ultrastable type Y zeolite as disclosed in U.S. Pat.No. 3,449,070 (US-Y) to provide equal activity and good gasoline octane.The PALMK for the catalyst in Table XVI was prepared by adding 9.0 kg ofkaolin clay (calcined 1/2 hour at 1650° F.) to 72 l of solutioncontaining 3,056 ml 37% HCl and boiling 7 hours under reflux. Aftercooling, the pH was adjusted to 7.0 with 30% NH₄ OH, filtered, andwashed 3 times with 12 gallons hot deionized water. 2,100 g dry basis(14,736 g as is) of this material was added to a blended slurry of 450 gSiO₂ /Al₂ O₃ basis ultrastable zeolite Y, the pH adjusted to 5.0 with10% HCl, 1,915 g Chlorhydrol added and the slurry spray dried. The US-Ysample was prepared by using only the alumina sol, US-Y and kaolin clay.Results, summarized in Table XVII, indicate similar activity andgasoline octane were achieved in spite of the greatly reduced US-Yusage.

EXAMPLE 33

Table VIII summarizes pilot unit results comparing silica sol boundcatalysts with/without PALMK. The PALMK for this preparation was made byaddition of 16 kg calcined (1/2 hour at 900° C.) kaolin clay to 48 l ofsolution containing 5.4 l 37% HCl and boiling under reflux for 48 hours,filtering and washing on the filter twice with 15 gallons hot deionizedwater. Note that this PALMK was not gelled by NH₄ OH addition. 2,280 g(dry basis) of this material and 800 g (SiO₂ /Al₂ O₃ basis) ultrastablezeolite Y were blended together in the minimum H₂ O and the pH adjustedto 4.0 with 20% H₂ SO₄. 9,200 g silica sol (about 10% by weight SiO₂)was added, the slurry mixed well and spray dried. The non-PALMKcontaining catalyst was prepared in the same fashion, except that moreultrastable Y was used and kaolin clay was also added instead of thePALMK. Pilot unit results on these catalysts, summarized in Table XVIII,indicate the PALMK containing catalyst produced a gasoline with improvedresearch and motor octane and equal conversion at 1/3 lower US-Y usage.

                  TABLE XI                                                        ______________________________________                                        Pore Size Distribution Date on NH.sub.4 OH Gelled                             Partially Acid Leached Metakaolin.sup.1                                       ______________________________________                                        BET Surface Area         488     m.sup.2 /g                                   Total N.sub.2 Pore Volume                                                                              0.3645  cc/g                                         Apparent P.V. more than 600 A° diameter                                                         0.0219  cc/g                                         Apparent P.V. less than 20 A° diameter                                                          0.1734  cc/g                                         Average Pore Diameter.sup.2                                                                            28.06   A°                                    (of pores up to 600 A°)                                                % of Surface Area in Pores:                                                   greater than 600 A°                                                                             0.14                                                 100-600 A°        0.44                                                  50-100 A°        1.48                                                  20-50 A°         72.22                                                less than 20 A°   25.72                                                ______________________________________                                         .sup.1 After drying 1 hour at 538° C.                                  .sup.2 Average pore diameter (APD) calculated as follows:                     ##STR1##                                                                 

                  TABLE XII                                                       ______________________________________                                        Effect of Gelation on Pore Structure of Partially                             Acid Leached Metakaolin.sup.1                                                                 Ungelled NH.sub.4 OH Gelled                                   ______________________________________                                        BET Surface Area  385.8      428.7                                            Total N.sub.2 Pore Volume                                                                       0.297      0.558                                            Apparent P.V. more than 600 A°                                                           0.0605     0.2883                                           Apparent P.V. less than 20 A°                                                            0.0587     0.2605                                           Average Pore Diameter                                                                           24.5       25.2                                             (of pores up to 600 A°)                                                % of Surface Area in Pores:                                                   greater than 600 A°                                                                      0.48       2.07                                             100-600 A° 0.12       3.06                                              50-100 A° 0.00       0.00                                              20-50 A°  69.54      20.73                                            less than 20 A°                                                                          29.86      74.14                                            ______________________________________                                         .sup.1 After heating 1 hour at 538° C.                            

                  TABLE XIII                                                      ______________________________________                                        Effect of Hydrothermal Treatment on Pore Structure of PALMK                                                 8 Hours,                                                            1 Hour,   732° C.                                  Pretreatment        538° C.                                                                          100% Steam                                      ______________________________________                                        BET Surface Area    296       103                                             Nitrogen Pore Volume                                                                              0.354     0.318                                           Average Pore Diameter                                                                             36.4      89.5                                            Pore Volume more than 600 A° Pores                                                         0.0843    0.0877                                          Pore Volume less than 18 A° Pores                                                          0.0       0                                               % of Surface Area in Pores.sup.1 :                                            greater than 600 A°                                                                        0.87      2.62                                            100-600 A°   2.52      24.03                                            50-100 A°   12.55     58.29                                            18-50 A°    78.53     25.11                                           ______________________________________                                         .sup.1 May total above or below 100% since surface area calculated from       distribution may be different than BET area.                             

                                      TABLE XIV                                   __________________________________________________________________________    Microactivity Data on PALMK With/Without Zeolites                                                             Commercial SiO.sub.2 --Al.sub.2 O.sub.3                          PALMK +                                                                             PALMK +                                                                              Gel Bound Catalyst                                          PALMK                                                                              15% US-Y                                                                            4.5% CREY                                                                            with about 12.5% CREY                         __________________________________________________________________________    MA Conditions:                                                                              500°, 32 WHSV, 3 C/O on Good Hope Feed after an 8                      hour,                                                                         732°, 100% Steam Deactivation.                           Vol. % Conv.  56.5 69.7  71.5   72.5                                          Mod. Conv. (incl. LCO), %                                                                   84.1 91.9  93.1   91.0                                          H.sub.2, wt. %                                                                              0.125                                                                              0.105 0.084  0.061                                         Tot. C.sub.1 + C.sub.2, wt. %                                                               2.05 2.67  2.19   2.44                                          Tot. C.sub.3, %                                                                             6.24 7.45  6.89   8.3                                           Tot. C.sub.4, %                                                                             10.29                                                                              11.40 10.48  9.9                                           C.sub.5 + Gaso., %                                                                          47.04                                                                              58.35 62.68  61.5                                          LCO, %        27.56                                                                              22.18 21.62  18.5                                          Total G + D, %                                                                              74.60                                                                              80.53 84.30  80.0                                          338° C. + Bottoms, %                                                                 15.92                                                                              8.15  6.89   9.0                                           Conv./Coke    11.5 14.5  14.9   14.8                                          __________________________________________________________________________

                                      TABLE XV                                    __________________________________________________________________________    PALMK with/without Binder                                                     __________________________________________________________________________    Composition      100% Gelled PALMK                                                                        85% Gelled PALMK                                                              15% Al.sub.2 O.sub.3 Sol                          Pretreatment     1 hour at 538° C.                                                                 1 hour at 538° C.                          Surface Area (m.sup.2 /g)                                                                      267        191                                               ABD/CD (Average Bulk Density/                                                                  .58/.93    .73/.93                                           Compacted Density)                                                            Davison Index/Jersey Index                                                                     25/1.6     13/0.6                                            __________________________________________________________________________

                                      TABLE XVI                                   __________________________________________________________________________    Use of PALMK Slurry to Improve Binding                                        __________________________________________________________________________    Composition   10.0% Al.sub.2 O.sub.3 Sol                                                              10.0% Al.sub.2 O.sub.3 Sol                                          12.5% CREY                                                                              15.0% PALMK Slurry (ungelled)                                       77.5% Kaolin Clay                                                                       12.5% CREY                                                                    62.5% Kaolin Clay                                     Calcination   1 hour at 677° C.                                                                1 hour at 677° C.                              ABD/CD        .86/.99   .82/.91                                               Davison Index/Jersey Index                                                                  7/1.0     3/0.4                                                 __________________________________________________________________________

                  TABLE XVII                                                      ______________________________________                                        Pilot Unit Comparison with/without PALMK                                      ______________________________________                                        Composition     15% Al.sub.2 O.sub.3 Sol                                                                  15% Al.sub.2 O.sub.3 Sol                                          15% US-Y    40% US-Y                                                          70% PALMK   45% Kaolin Clay                                   Deactivation:   12 hours, 20% steam after 1 hour at                                           677° C. thermal treatment.                             Pilot Unit Conditions:                                                                        40 WHSV, 3 C/O, 496° C. on                                             Sohio Heavy Gas Oil.                                          Vol. % Conversion                                                                             53.5        58.0                                              H.sub.2, wt. %  0.08        0.04                                              C.sub.1 + C.sub.2, wt. %                                                                      1.16        .076                                              Total C.sub.3, vol. %                                                                         6.5         5.7                                               Total C.sub.4, vol. %                                                                         9.6         10.1                                              C.sub.5 + Gasoline, vol. %                                                                    42.0        47.0                                              RON (Research Octane No.)                                                                     92.2        92.1                                              Light Cycle Oil, vol. %                                                                       16.3        15.9                                              338° C. + Residue, vol. %                                                              28.2        26.1                                              Coke, wt. %     4.2         4.3                                               ______________________________________                                    

                  TABLE XVIII                                                     ______________________________________                                        Use of PALMK to Enhance Gasoline Octane                                       at Reduced US-Y Usage                                                         ______________________________________                                        Composition     23% SiO.sub.2 Sol                                                                         25% SiO.sub.2 Sol                                                 20% US-Y    30% US-Y                                                          57% PALMK   45% Kaolin Clay                                   Hydrothermal Treatment:                                                                       12 hours, 827° C., 20 steam.                           Pilot Unit Conditions:                                                                        40 WHSV, 3 C/O, Sohio Feed,                                                   510° C.                                                Vol. % Conversion                                                                             55.0        55.0                                              Total C.sub.3, vol. %                                                                         6.1         5.1                                               Total C.sub.4, vol. %                                                                         11.0        9.8                                               C.sub.5 + Gasoline, vol. %                                                                    39.5        42.0                                              RON             90.7        89.0                                              MON             79.1        78.4                                              LCO, vol. %     30.2        30.8                                              338° C. + Residue, vol. %                                                              14.8        14.1                                              ______________________________________                                    

EXAMPLE 34

A base/acid reacted kaolin prepared in accordance with the teachings ofU.S. Pat. No. 3,406,124 was produced as follows: 116.16 g kaolin claywas slurried in 384.9 g deionized water with rapid agitation. A solutionof 5.1 g NaOH in 5.1 g deionized water was added to the clay slurry andthen hot aged for 1 hour at 200° F. After cooling to 150° F., 30.3 g 18wt. % H₂ SO₄ was added to pH 5.2. The pH was then adjusted to 7.0 with2N NaOH. The slurry was filtered, washed three times with 1/2 l hotdeionized water and dried overnight at 250° F. The sample was crushedthrough a 20 mesh screen, then exchanged twice with 0.25 parts (NH₄)₂SO₄ /part clay/5 parts water for 1/2 hour at 150° F., filtered, washed1X 1/2 l hot deionized water (3 times 1/2 l hot deionized water afterthe second exchange) and oven dried overnight at 250° F.

The properties are summarized in Table XIX. Compared with PALMK, thismaterial is much lower in surface area, lower in N₂ pore volume, has amuch higher average pore diameter and is considerably higher in Al₂ O₃content.

                  TABLE XIX                                                       ______________________________________                                        Properties of Composition Produced by                                         Method of U.S. Pat. No. 3,406,124                                             ______________________________________                                        Surface Area, m.sub.2 /g                                                                         21                                                         N.sub.2 PV, cc/g   0.04                                                       Avg. Pore Diameter, A°                                                                    76                                                         ______________________________________                                    

EXAMPLE 35

An acid reacted clay product was prepared in accordance with theteachings of U.S. Pat. No. 2,485,626 as follows: 10 g of kaolin clay wascalcined for 2 hours at 1350° F. The calcined clay was mixed with 222.2ml of 18 wt. % H₂ SO₄ solution and reacted at room temperature (75° F.)for 48 hours with slow agitation: The resulting reaction mixture wasdivided into two samples.

Sample 1 was filtered to remove the solid product which was washed twicewith 0.5 l of deionized water and oven dried at 250° F. The resultingproduct possessed an Al₂ O₃ content of 40.52 wt. % and a surface area of34 m² /g.

Sample 2 was combined with sufficient (14 wt. %) NH₄ OH solution toadjust the pH to 9.0, filtered to recover solids which were washed onewith 0.5 l water, adjusted to pH 9 with NH₄ OH, and once with 0.5 ldeionized water. The resulting product was oven dried at 250° F. andfound to possess an Al₂ O₃ content of 43.3 wt. %, and a surface area of46 m² /g.

The above Examples clearly indicate that valuable catalyst compositionsmay be obtained using the teachings of my invention.

I claim:
 1. A method for cracking hydrocarbons which comprises reactinga hydrocarbon feedstock under catalytic cracking conditions with acatalyst which comprises an acid reacted metakaolin composition having amole composition of about 0.8 to 1.0 Al₂ O₃.2 SiO₂ and characterized bya surface area of above about 150 m² /g.
 2. The method of claim 1wherein the catalyst is further characterized by a total pore volume ofabout 0.15 to 0.50 cc/g, an average pore diameter of about 20 to 40 Å,and a surface area of up to about 500 m² /g.
 3. The method of claim 2wherein said catalyst is further characterized by having above about 90percent of the surface area in pores less than 50 Å in diameter.
 4. Themethod of claim 1 wherein said catalyst is reacted with a base and has atotal pore volume of up to about 0.7 cc/g.
 5. The method of claim 1wherein said catalyst is reacted at a temperature of above about 300° C.and has a surface area of below about 500 m² /g.
 6. The method of claim1 wherein said catalyst has a particle size range of from about 20 to200 microns.
 7. The method of claim 1 wherein the catalyst contains aninorganic oxide component selected from the group consisting ofcrystalline zeolite, silica, alumina, silica-alumina hydrogels andhydrosols, clays and mixtures thereof.